Two former California police officers seen in a video beating a mentally ill homeless man unconscious during an arrest were acquitted Monday of killing him.

The Orange County jury’s verdict, after two days of deliberations, brought a close to a case that set off an emotional debate on a police officer’s right to use force and the special needs of people with psychiatric disorders. The case also fueled a nationwide conversation on how to train police to work with mentally ill suspects.

The decision upheld the defense’s argument that the two Fullerton police officers, Manuel Ramos and Jay Cicinelli, had acted in line with their training and their professional right to use force when they beat Kelly Thomas, a homeless man diagnosed as a schizophrenic, during a police altercation on a summer night in 2011. It dealt a blow to the prosecution’s contention that the incident sets a precedent for allowing police to deal brutally with the mentally ill, putting a vulnerable population – prone to erratic behavior during arrest – at risk of the same fate as Mr. Thomas.

Mr. Ramos was acquitted of second-degree murder and involuntary manslaughter, and Mr. Cicinelli was acquitted of involuntary manslaughter and excessive use of force. A third officer, Joseph Wolfe, was also accused of involuntary manslaughter, but the district attorney’s office said it would drop the charge against Mr. Wolfe, following the Monday verdicts.

Mr. Thomas, the father, has said that he hopes that the US Justice Department will file federal charges against the officers. The FBI has been pursuing its own investigation of the high-profile case.

On July 5, 2011, at 8:23 p.m., the Fullerton Police Department received a call reporting a “homeless” man – “disheveled and shirtless” – who was “looking in car windows and pulling on handles of parked cars” at a bus depot, according to the Orange Country District Attorney’s office. Six officers, Mr. Ramos and Mr. Cicinelli included, responded.

At first, all was calm. The officers ordered Thomas to sit on the curb and put his hands on his knees. He eventually complied but also appeared to be confused, at times vocally belligerent, the district attorney’s office said.

Then, in circumstances that will likely remain unclear, the altercation turned violent. The defense said that Thomas did not follow police orders to sit still; the prosecution said that Thomas did not understand and could not follow those orders.

What was clear was what followed, since it was recorded from start to finish on a 33-minute surveillance video that would later fuel public outrage and push the case to trial: Ramos put on latex gloves and then put his fists in Thomas’s face, saying, "see these fists?...They're getting ready to ---- you up." For nine minutes and 40 seconds, the six officers pummeled Thomas to the ground, with Ramos delivering volleys of punches and beating Thomas with his baton and Cicinelli tasing the homeless man twice in the face. In parts of the footage that particularly incited public anger, Thomas repeatedly cries out for his father to help him, as well as screams again and again “I’m sorry” and “please, I can’t breathe.”

The altercation left Thomas unconscious, and he did not regain consciousness after being transferred to a local hospital. He died five days later.

To the prosecution, and to protesters that rallied to Thomas’s cause during the trial, the video showed two police officers abusing their right to force against an unarmed man who “posed a low-level threat,” according to the district attorney’s office.

The defense said that cops must protect themselves when they believe they are in danger, without fear of prosecution for handling the incident with force.